Sectional boiler

ABSTRACT

A sectional boiler burning fluid fuels comprises a core combustion chamber and forward and return flue passages forming concentric jackets surrounding the combustion chamber. The flue passages are interconnected only in the front section of the boiler and are radially bounded by inner and outer concentrically arranged water compartments which are connected to forward and return flow connecting pipes. The respective flue passages are separated from each other by radial passages which connect the water compartments. Baffles are positioned in the flue passages to further increase the heat transfer transmission therein.

United States Patent [72] Inventor Kurt Erich Nauert Walldorf, Germany [21] Appl. No. 874,832 [22] Filed Nov. 7, 1969 [45] Patented Nov. 9, 1971 [73] Assignee Strebelwerk, G.m.b.H.

Mannheim, Germany [32] Priority Nov. 15, 1968 [3 3 1 Germany [31] P18 09 073.8

[54] SECTIONAL BOILER 3 Claims, 4 Drawing Figs.

[52] US. Cl 122/225 R, 122/367 R [51] Int. Cl F22b 7/12 [50] Field of Search 122/223, 225 R, 367 R [56] References Cited UNITED STATES PATENTS 2,316,603 4/1943 Livar 122/225 FOREIGN PATENTS 1,484,085 5/1967 France 122/225 451,820 8/1936 Great Britain 122/225 Primary Examiner-Kenneth W. Sprague Attorney-Otto John Munz ments. Baffles are positioned in the flue passages to further increase the heat transfer transmission therein.

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ATTORNEY PATENIFU rmv 9 mm SHEET 2 [1F 3 w N w w KURT ERICH NAUERT i ATTORNEY PATENTEUNnv 9mm 3518572 sum 3 BF 3 KURT ERICH NAUERT ATTORNEY SECTIONAL BOILER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to boiler structures, and more particularly to provide improvements in a sectional boiler burning fluid fuels.

2. Description of the Prior Art In a sectional boiler, in order to be able to transfer maximum quantities of heat from the exhaust gases to the water, maximum temperature differentials between exhaust gas and water are required.

For this purpose the return flue passages which conduct the hottest exhaust gases have already been disposed in the lower cold region of the boiler. This has the advantage that the cold return flow water is quickly heated above the temperature of the point of condensation of the exhaust gases. This type of boiler construction has, however, the disadvantage that for a further heating of the water in the upper region of the boiler, only previously cooled exhaust gases are available for the forward flue passages. This causes a substantial temperature differential. Consequently, the heat transfer is low in this region.

On the other hand, it is very difficult to arrange the hot return flue passages at the top and the cooler forward flue passages on the bottom since the cooled exhaust gases of the forward flue passages must not be conducted through the cold boiler zones in which the cooled water of the return flow flows if it is intended to avoid falling below the point of condensation.

SUMMARY OF THE INVENTION The present invention has the object of providing a structural arrangement of the return and forward flue passages whereby on each heat exchange surface of the boiler, a maximum temperature differential is available and thus drops below the point of condensation are avoided.

According to the present invention, this is achieved in a sectional boiler of the type described by providing two forward flue passages and at least four return flue passages situated close to the forward and reverse water flow connecting pipes and further, by providing on either side of the boiler, return flue passages in the front section being connected via a flue reversing passage to one of the forward flue passages joining the exhaust gas collector.

The hot exhaust gases are thus distributed to at least two return flue passages which are situated near the forward flow connecting pipe and to at least two further return flue passages which are arranged close to the reverse flow connecting pipe. In the front section at least four return flue passages are connected to two forward flue passages that extend along the rightand left-hand sides of the boiler at approximately half the height of the boiler which passages lead to the waste gas collector. By virtue of this tortuous path for the exhaust gases, the cold water entering the boiler from the reverse flow connecting pipe is first acted upon by the hot exhaust gases of at least two lower return flue passages. It is thus heated above the temperature of the point of condensation to such a degree that upon further heating of the exhaust gases in the forward flue passages, no exhaust gas condensations in these forward flue passages will occur. The boiler water reaches the maximum temperature by contact with at least two hot upper return flue passages, and a sufficient temperature differential is produced in each heat exchange region.

If the forward and reverse flow connecting pipes are situated outside the various sections of the boiler, the construction of the central heating boiler according to the present invention will be simplified if only two return flow passages are provided. One of which is adjacent a forward flow connecting pipe and the other of which is adjacent a reverse flow connecting pipe. Thus, they are situated partially in the right-hand and partially in the left-hand side of the boiler.

In order to be able to remove the hot water in the shortest possible time out of the sections and simultaneously to avoid unnecessary flow resistances, the connecting pipes are advantageously fitted inside the sections themselves; that is, two pairs of return flow passages will then be provided on either side of the forward and reverse flow connecting pipes respectively.

For the purpose of cleaning the forward and return flue passages, cleaning apertures have been provided in the front section. Cleaning is facilitated if each of the lower return flue passages also has in the rear section, a cleaning aperture which can be closed by a plug.

For further improving the heat exchange in the forward and return flue passages, baffle plates are advantageously inserted therein which carry ribs that increase the heat transmission and that extend in the direction of the flow and project between similar ribs of the inner walls of the passages. These inserted baffle plates preferably lie loosely in the passages and at least one of the ribs of the baffle plates is formed as an elongated supporting rib.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment by way of example of the present invention is shown diagrammatically in the accompanying drawings in which:

FIG. 1 is an axial sectional view through a sectional boiler in accordance with the invention on line [-1 of FIG. 2;

FIG. 2 is a plan view of a middle section of the boiler of FIG.

FIG. 3 is a rear elevation of the rear section of the boiler of FIG. 1, as viewed from the combustion chamber; and

FIG. 4 is forward or return flue passage with an inserted baffle plate on an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 of the drawings, a cylindrically shaped boiler burning fluid fuels comprises a central core combustion chamber 2, middle sections 4, a front section 6, a rear section 8 and an exhaust gas collector or flue 10. The boiler is surrounded by concentrically arranged jackets for the water compartments and the flue passages as will be explained hereinafter. A burner not shown is inserted in the opening. The hot exhaust fuel gases of the combustion pass from the combustion chamber 2 via flue reversing passages 12 into the upper return flue passages 14 and 16 (FIG. 2) and the lower return flue passages 18 and 20. In the from section 6, these four return flue passages are connected by flue reversing passages 13 to two forward flue passages 22 and 24 which communicate with the exhaust gas collector 10. Thus, the heating gases (exhaust gases) exit through flue 10 which connects with a stack (not shown).

The water flows via the reverse flow pipe 26 into the outer peripheral water compartment 28 and the inner peripheral water compartment 30. These water compartments 28 and 30 are interconnected via radial passages 32 which separate the exhaust gas passages from each other. The heated water emerges from the boiler through the forward flow pipe 34.

At first the in flowing water is heated by the lower return flue passages 18 and 20 to above the temperature of the point of condensation of the exhaust gases. It is then heated further by the less hot exhaust gases of the forward flue passages 22 and 24 without any risk that exhaust gas condensation will occur in these exhaust gas passages 22 and 24. Finally, the water is heated to its final temperature when it comes into contact with the hot exhaust gases of the upper return flue passages 16 and 14. In this manner it is ensured by the abovedescribed arrangement of the exhaust gas passages that a maximum temperature differential is always present on the heat exchange surfaces between water and exhaust gas.

A further improvement in the economy of the central heating boiler according to the invention can be achieved, as shown in FIG. 4, by the arrangement of an insert baffle plate 40 in a exhaust passage which is bounded by peripheral water compartments 28 and 30 and by radial passages 32. This insert baffle plate 40 has a series of radial ribs 42, one of which is constructed as a supporting rib 44. These ribs provide an increased heat transfer surface by their construction that extends into the flue passages. A further support is provided by the extension 48 of the inserted plate. The individual ribs 42 protrude between ribs 46 which provide additional heat transfer surfaces and which are also parallel to the axis. Ribs 46 protrude from the walls of the water compartments 28 and 30 into the exhaust gas passage. By the use of the baffle plate 40 a considerable increase in the heat exchange is achieved because the baffle plate radiates the heat absorbed to the ribs 46 and the walls of the water compartments 28 and 30.

For cleaning the exhaust gas passages the front section 6 has cleaning apertures 50 and 52 closed by detachable covers When cleaning, a large amount of dirt drops via the flue reversing passage of the front section into the lower return flue passages 18 and 20. When cleaning, this dirt can easily be pushed to the back by the brushes and it is therefore advantageous to provide at the ends of the lower return flue passages cleaning aperture 54 in the rear section 8. Each of the cleaning apertures 54 is provided with a refractory plug 56.

lclaim:

1. A sectional liquid fuel burning boiler comprising; a forward and a rear member, a combustion chamber, a plurality of middle sections surrounding the said combustion chamber in parallel axial configurations;

An exhaust collector, primary and secondary forward and return flow flue gas passages, axially and parallely arranged adjacent to each other and connected with each other in the said forward member only;

A plurality of peripherally arranged inner and outer water chambers with connecting forward and return flow water flow pipes surrounding said flue gas passages to permit the forward and return flow of water, said flue gas passages separated by a plurality of radial chambers, conduit means connecting said primary and forward gas passages for the progressively cooled gases with said exhaust collector, and connecting said secondary and return flue gas passages for the hot flue gases to the combustion chamber, said boiler having two return hot gas passages adjacent to the said forward connecting water flow pipe,

and two return flow hot gas passages provided adjacent to the said return flow water pipes;

Two of the forward flow gas passages being located between two each return flow gas passages respectively at to each other at the midsection of the boiler.

2. A sectional liquid fuel burning water boiler comprising a combustion chamber; a plurality of flue gas passages spaced from each other and connected with said combustion chamber;

A plurality of water jackets surrounding said combustion chamber and said flue gas passages;

A plurality of hot and cold water conducting passages spaced from each other connected with said water jackets; and

Condensation avoiding means connecting said plurality of water jackets with said water conducting passages spaced from each other and relative to the said flue gas passages, arranged to avoid contact of partially cooled hot flue gases with the said cold water return passages to prevent reduction of the temperature of the said partially cooled hot flue gases below the dew point.

3. A boiler as defined in claim 2, and further comprising baffle means in said flue passages spanning a part of the crosssectional area thereof to increase the heat transfer surface thereof. 

1. A sectional liquid fuel burning boiler comprising; a forward and a rear member, a combustion chamber, a plurality of middle sections surrounding the said combustion chamber in parallel axial configurations; An exhaust collector, primary and secondary forward and return flow flue gas passages, axially and parallely arranged adjacent to each other and connected with each other in the said forward member only; A plurality of peripherally arranged inner and outer water chambers with connecting forward and return flow water flow pipes surrounding said flue gas passages to permit the forward and return flow of water, said flue gas passages separated by a plurality of radial chambers, conduit means connecting said primary and forward gas passages for the progressively cooled gases with said exhaust collector, and connecting said secondary and return flue gas passages for the hot flue gases to the combustion chamber, said boiler having two return hot gas passages adjacent to the said forward connecting water flow pipe, and two return flow hot gas passages provided adjacent to the said return flow water pipes; Two of the forward flow gas passages being located between two each return flow gas passages respectively at 180* to each other at the midsection of the boiler.
 2. A sectional liquid fuel burning water boiler comprising a combustion chamber; a plurality of flue gas passages spaced from each other and connected with said combustion chamber; A plurality of water jackets surrounding said combustion chamber and said flue gas passages; A plurality of hot and cold water conducting passages spaced from each other connected with said water jackets; and Condensation avoiding means connecting said plurality of water jackets with said water conducting passages spaced from each other and relative to the said flue gas passages, arranged to avoid contact of partially cooled hot flue gases with the said cold water return passages to prevent reduction of the temperature of the said partially cooled hot flue gases below the dew point.
 3. A boiler as defined in claim 2, and further comprising baffle means in said flue passages spanning a part of the cross-sectional area thereof to increase the heat transfer surface thereof. 